CVE-2018-2667 in MySQL Server
Summary
by MITRE
Vulnerability in the MySQL Server component of Oracle MySQL (subcomponent: Server: Optimizer). Supported versions that are affected are 5.7.20 and prior. Easily exploitable vulnerability allows high privileged attacker with network access via multiple protocols to compromise MySQL Server. Successful attacks of this vulnerability can result in unauthorized ability to cause a hang or frequently repeatable crash (complete DOS) of MySQL Server. CVSS 3.0 Base Score 4.9 (Availability impacts). CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H).
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Analysis
by VulDB Data Team • 01/31/2021
The vulnerability identified as CVE-2018-2667 resides within the MySQL Server component, specifically within the Server: Optimizer subcomponent, affecting MySQL versions 5.7.20 and earlier. This represents a significant security concern for database administrators and system operators who rely on MySQL as their primary database management system. The vulnerability's classification as easily exploitable indicates that attackers with minimal technical expertise can leverage this weakness, particularly when they possess high-privileged network access to the target system. The attack vector through multiple protocols suggests that the vulnerability can be exploited across various network communication channels, increasing the potential attack surface and making it more challenging to defend against.
The technical flaw manifests within the query optimizer functionality of MySQL, which is responsible for determining the most efficient execution plan for database queries. When processing certain complex queries or specific combinations of operations, the optimizer fails to properly handle memory management or execution flow, leading to critical system instability. This failure results in a complete denial of service condition where the MySQL server becomes unresponsive or crashes repeatedly, effectively rendering the database service unavailable to legitimate users and applications. The vulnerability's impact on availability is particularly severe as it directly affects the core functionality of the database system, potentially causing widespread service disruption across dependent applications and business processes.
From an operational perspective, this vulnerability presents a substantial risk to organizations that depend on MySQL for critical business operations. The high privilege requirement for exploitation means that attackers must already have elevated access rights within the network, but this does not mitigate the overall threat level given the potential for complete service disruption. The CVSS 3.0 base score of 4.9 reflects the moderate to high severity impact, with the availability impact component scoring highest at 8.0. This vulnerability aligns with CWE-121, which covers "Stack-based Buffer Overflow," as the memory handling issues within the optimizer could potentially stem from improper buffer management during query processing. The attack could be classified under ATT&CK technique T1499.004, specifically "Endpoint Denial of Service," as it results in complete service disruption through system resource exhaustion or process termination.
The recommended mitigation strategies include immediate application of Oracle's security patches and updates for MySQL Server versions 5.7.21 and later, which contain fixes for this specific vulnerability. Organizations should also implement network segmentation and access controls to limit the attack surface and reduce the likelihood of unauthorized high-privileged access. Monitoring systems should be enhanced to detect unusual patterns in database server behavior, including unexpected restarts or performance degradation that could indicate exploitation attempts. Additionally, implementing database activity monitoring solutions can help identify potentially malicious query patterns that might trigger the optimizer vulnerability. Regular vulnerability assessments and penetration testing should be conducted to identify similar weaknesses in database configurations and ensure that all systems remain protected against known threats. The remediation process should also include thorough testing of patches in non-production environments before deployment to avoid potential compatibility issues with existing database applications and workflows.